Large Antarctic glacier thinning 4 times faster than it was 10 years ago: “Nothing in the natural world is lost at an accelerating exponential rate like this glacier.”

Calculations based on the rate of melting 15 years ago had suggested the glacier would last for 600 years. But the new data points to a lifespan for the vast ice stream of only another 100 years.

The rate of loss is fastest in the centre of the glacier and the concern is that if the process continues, the glacier may break up and start to affect the ice sheet further inland.

One of the authors, Professor Andrew Shepherd of Leeds University, said that the melting from the centre of the glacier would add about 3cm to global sea level.

“But the ice trapped behind it is about 20-30cm of sea level rise and as soon as we destabilise or remove the middle of the glacier we don’t know really know what’s going to happen to the ice behind it,” he told BBC News.

Antarctica is disintegrating much faster than almost anybody imagined. In 2001, the IPCC “consensus” said neither Greenland nor Antarctica would lose significant mass by 2100. They both already are. As Penn State climatologist Richard Alley said in March 2006, the ice sheets appear to be shrinking “100 years ahead of schedule.”

Pine Island Glacier is where the first “A” in “Antarctica” in the figure above [see figure on right, click to enlarge]. It is of special interest, as the BBC notes:

Pine Island glacier has been the subject of an intense research effort in recent years amid fears that its collapse could lead to a rapid disintegration of the West Antarctic ice sheet.

The rest of this post will survey what we now know about the increasingly unstable West Antarctic ice sheet (WAIS) and the threat it poses to humanity “” or is that the threat humanity poses to it? “” if we continue on our current suicidal emissions path. Regular readers can skip the rest of this post since I’m mostly excerpting, “Q: How much can West Antarctica plausibly contribute to sea level rise by 2100?” [A: 3 to 5 feet].

A 2007 study found “The current loss of mass from the Amundsen Sea embayment of the West Antarctic ice sheet [WAIS] is equivalent to that from the entire Greenland ice sheet” (see the new survey report Antarctic Climate Change and the Environment draft here). And WAIS’s 2007’s ice loss was 75% higher than 2006’s (see “The Antarctic ice sheet hits the fan“).

The warming of the WAIS is most worrisome (at least for this century) because it’s going to disintegrate long before the East Antarctic Ice Sheet does “” since WAIS appears to be melting from underneath (i.e. the water is warming, too), and since, as I wrote in the “high water” part of my book, the WAIS is inherently less stable:

Perhaps the most important, and worrisome, fact about the WAIS is that it is fundamentally far less stable than the Greenland ice sheet because most of it is grounded far below sea level. The WAIS rests on bedrock as deep as two kilometers underwater. One 2004 NASA-led study found that most of the glaciers they were studying “flow into floating ice shelves over bedrock up to hundreds of meters deeper than previous estimates, providing exit routes for ice from further inland if ice-sheet collapse is under way.” A 2002 study in Science examined the underwater grounding lines-the points where the ice starts floating. Using satellites, the researchers determined that “bottom melt rates experienced by large outlet glaciers near their grounding lines are far higher than generally assumed.” And that melt rate is positively correlated with ocean temperature.

The warmer it gets, the more unstable WAIS outlet glaciers will become. Since so much of the ice sheet is grounded underwater, rising sea levels may have the effect of lifting the sheets, allowing more-and increasingly warmer-water underneath it, leading to further bottom melting, more ice shelf disintegration, accelerated glacial flow, and further sea level rise, and so on and on, another vicious cycle. The combination of global warming and accelerating sea level rise from Greenland could be the trigger for catastrophic collapse in the WAIS(see, for instance, here).

You can read every thing a laymen could possibly want to know about what the recent study on Antarctic warming does and doesn’t show at RealClimate here.

Our data provide direct evidence for orbitally induced oscillations in the WAIS, which periodically collapsed, resulting in a switch from grounded ice, or ice shelves, to open waters in the Ross embayment when planetary temperatures were up to 3 °C warmer than today and atmospheric CO2 concentration was as high as 400 p.p.m.v.

We’ll be at 400 ppm by 2020. We’re on track to be more than 5°C warmer by 2100. So the first paper doesn’t seem terribly reassuring.

“¦ the WAIS will begin to collapse when nearby ocean temperatures warm by roughly 5 °C. Global climate and regional ocean modelling is needed to predict when and if future ocean temperatures and melt rates under the major Antarctic ice shelves will increase by these amounts, and if so, for how long.

I’m familiar with the Pollard/DeConto work. They previewed it last fall at an annual science workshop I organize on West Antarctic research. Their model lacks the detail to get the fastest dynamic responses, so the 0.5m/century rate for sea level rise should only be viewed as a lower bound (and a poor one, at that).

Their model is better at getting the longer-term quasi-equilibrium response (it just takes their model a little longer to get there), so it ‘s very interesting that they demonstrate the sensitivity to the ocean temperature. That thinking is certainly where Antarctic scientists are being led by both data and models.

Moreover, the entire WAIS need not collapse for it to contribute to catastrophic sea level rise this century.

The Antarctic Peninsula alone contains “a total volume of 95,200 km3 (equivalent to 242 mm of sea-level; Pritchard and Vaughan, 2007), roughly half that of all glaciers and ice caps outside of either Greenland or Antarctica” (see Chapter 5 here) “” that would be more than 9 inches of sea level rise from a region of WAIS losing its protective ice shelves on both sides at an alarming pace.

But it is westernmost part of WAIS, that borders on the Amundsen Sea, and that includes Pine Island, that we need to worry most about, as AP reported earlier this year:

Glaciers in Antarctica are melting faster and across a much wider area than previously thought, a development that threatens to raise sea levels worldwide and force millions of people to flee low-lying areas, scientists said Wednesday.

Researchers once believed that the melting was limited to the Antarctic Peninsula, a narrow tongue of land pointing toward South America. But satellite data and automated weather stations now indicate it is more widespread.

The melting “also extends all the way down to what is called west Antarctica,” said Colin Summerhayes, executive director of the Britain-based Scientific Committee on Antarctic Research.

“That’s unusual and unexpected,” he told the Associated Press in an interview.

By the end of the century, the accelerated melting could cause sea levels to climb by 3 to 5 feet “” levels substantially higher than predicted by a major scientific group just two years ago….

The biggest of the western glaciers, the Pine Island Glacier, is moving 40% faster than it was in the 1970s, discharging water and ice more rapidly into the ocean, said Summerhayes, a member of International Polar Year’s steering committee.

The Smith Glacier, also in west Antarctica, is moving 83% faster than in 1992, he said.

The glaciers are slipping into the sea faster because the floating ice shelf that would normally stop them “” usually 650 to 980 feet thick “” is melting. And the glaciers’ discharge is making a significant contribution to increasing sea levels.

So we have the serious potential for 3 to 5 feet of sea level rise just from WAIS this century “” and that is on top of whatever we get from thermal expansion of the ocean and Greenland. And on top of whatever we get from the melting of the inland glaciers, whose contribution was recently increased:

New research published this month in the journal Geophysical Research Letters found that melting glaciers will add at least 7 inches to the world’s sea level “” and that’s if carbon dioxide pollution is quickly capped and then reduced.

Far more likely is an increase of at least 15 inches and probably more just from melting glaciers, the journal said.

So it increasingly looks like we are facing a very serious risk of more than 5 feet of total sea level rise by 2100 on our current emissions path.

We are in a race between tipping points in nature and in our political systems. Can we phase out coal-fired power plants before the melting of the Greenland ice sheet becomes irreversible? Can we gather the political will to halt deforestation in the Amazon before its growing vulnerability to fire takes it to the point of no return? Can we help countries stabilize population before they become failing states?

We have the technologies to restore the earth’s natural support systems, to eradicate poverty, to stabilize population, and to restructure the world energy economy and stabilize climate. The challenge now is to build the political will to do so. Saving civilization is not a spectator sport. Each of us has a leading role to play.

A couple of years ago, I attended a lecture given by Dr. Jeff Severinghaus at the Scripps Institution of Oceanography. When the topic of sea-level rise came up, he said (with all the appropriate caveats, of course) that he foresaw a sea-level rise of 2-6 feet over the next century. I’m not going to put words in his mouth, but I rather suspect that he’s leaning toward the higher end of that range now.

http://www.guardian.co.uk/environment/2009/aug/13/coal-stations-activism
…
He added: “There is no such thing as a free lunch and we’re not going to get a free lunch around coal. So my view would be if the government wants to provide a lightning rod for public disagreement or dissent around coal, then start building a new coal-fired power station, and the orang-utan costumes will be dusted off from around the planet and people will come and say this is wrong. And two wrongs don’t make a right. People say “oh there is one a week opening in China”. And? I don’t think that’s a good enough reason.”
…
Day said: “Politicians are there to make the hard decisions. And there are some really hard decisions coming up. And they’re hard because they’re not the kind of decisions that individuals particularly want to have taken. How many short- to medium-haul flight holidays does anyone really need to have a year? Ed Miliband interestingly said something like ‘don’t worry your holiday flights are safe with me’. But we know that we need to be encouraging and supporting, through a combination of stick and carrot, some change to behaviours.”

In Lovelock’s view, the scale of the catastrophe that awaits us will soon become obvious. By 2020, droughts and other extreme weather will be commonplace. By 2040, the Sahara will be moving into Europe, and Berlin will be as hot as Baghdad. Atlanta will end up a kudzu jungle. Phoenix will become uninhabitable, as will parts of Beijing (desert), Miami (rising seas) and London (floods). Food shortages will drive millions of people north, raising political tensions. “The Chinese have nowhere to go but up into Siberia,” Lovelock says. “How will the Russians feel about that? I fear that war between Russia and China is probably inevitable.” With hardship and mass migrations will come epidemics, which are likely to kill millions. By 2100, Lovelock believes, the Earth’s population will be culled from today’s 6.6 billion to as few as 500 million, with most of the survivors living in the far latitudes — Canada, Iceland, Scandinavia, the Arctic Basin.

By the end of the century, according to Lovelock, global warming will cause temperate zones like North America and Europe to heat up by fourteen degrees Fahrenheit, nearly double the likeliest predictions of the latest report from the Intergovernmental Panel on Climate Change, the United Nations-sanctioned body that includes the world’s top scientists. “Our future,” Lovelock writes, “is like that of the passengers on a small pleasure boat sailing quietly above the Niagara Falls, not knowing that the engines are about to fail.” And switching to energy-efficient light bulbs won’t save us. To Lovelock, cutting greenhouse-gas pollution won’t make much difference at this point, and much of what passes for sustainable development is little more than a scam to profit off disaster.

Lovelock has a nasty habit of being right, and seeing things first.

Of course, he could also be underestimating the problem, out of normal scientific conservatism.

What a shame that a human race that could produce such a man can also produce Mark Morano.

We need to seize the coal fired power plants, and convert them to biomass or biochar fuel, enhanced efficiency via oxyfuel combustion and a topping cycle, and subsequent carbon capture and storage.

Most coal plants are located on rivers for cooling water. All of the territory upstream of the coal plants on those rivers becomes potential biomass or biochar collection area. Biomass and biochar could be transported down the rivers to the converted coal fired power plants by barge – the cheapest form of transport.

By doing this, we could transform the worst problem (coal fired power plants) into the best solution (carbon negative power plants). With these converted coal fired power plants, we could put a billion tons of carbon per year back underground, in the U.S., and power our society this way at the same time.

Seize the coal plants, and convert them. Pay for the conversion by increasing their efficiency.

As I understand it, current climate models include simulation for a number of factors: ice melting due to atmospheric and marine heat transport and direct solar irradiation, geological heat inputs, mybe physical and biological feedbacks and of course the various contributions to heat storage. Right?

Now, about the estimation of sea level rise the factors considered are ice melting and the thermic expansion of oceans. Right?

A question has been troubling me since some time: when the ice sheet disappears from Greenland or Antarctica this can have a very pronounced geological effect too. Like a raft which suddenly becomes much lighter these 2 lands would pop up like a cork, thus exacerbating global sea level rises. I suspect this could be a fairly quick process, with a response closely following disappearance of the ice layer. Has this been considered in models and predictions?

forgot: at the same time, when Greenland and Antarctica pop up, the ocean and sea floors will sink, putting a lot of weight on all coastal areas and the edges of continental shelves. This might bend continents mybe .. and thus cause a lot of earthquakes in addition of exacerbated sinking of coastal areas. (are we experiencing an increasing trend in earthquakes too?)

One additional geologic effect is that the sudden increase in surface temperature will slowly propagate to the inner part of faults changing the properties of rocks and allowing faults to move faster .. and thus changing earthquake patterns. This is a very slow process, I imagine, probably negligible at the time scale of global warming.

yet another thing sorry. Greenland and Antarctica are “caved in” by the enormous weight of the ice sitting on them. Like flexible rafts, the center of the continents should be sinking more than the edges. When and if they “pop up” in response to the decrease of ice they should change shape, with their center part raising higher .. This should nonlinearly increment the speed of ice flow, compounding the release of methane and the albedo effect and making the tipping point sharper.

We are in a race between tipping points in nature and in our political systems. Can we phase out coal-fired power plants before the melting of the Greenland ice sheet becomes irreversible? Can we gather the political will to halt deforestation in the Amazon before its growing vulnerability to fire takes it to the point of no return? Can we help countries stabilize population before they become failing states?

We have the technologies to restore the earth’s natural support systems, to eradicate poverty, to stabilize population, and to restructure the world energy economy and stabilize climate. The challenge now is to build the political will to do so. Saving civilization is not a spectator sport. Each of us has a leading role to play.

This news is certainly disturbing. What has disturbed be the most in the last few weeks in watching the utter insanity around the Health Care reform debate. Watching the inability of of much of the public to engage in any kind of thoughtful discussion on this matter leaves me doubting that the discussion will be any better and perhaps more unhinged when it comes to meaningful climate change legislation.

George, that’s a great point. Its disturbing to watch it play out. One can only hope you’re wrong about what will happen with the climate legislation. On the bright side its already through the house and its just the Senate remaining for the climate change stuff (keeping fingers crossed).